Specifications

possible circuit density is also much higher, allowing for a much more compact

circuit layout. As far as the aforementioned durability, a PCB would be the least

susceptible to have wires or components come undone due to normal use of the

portable unit. One possible disadvantage of a PCB is its relatively high cost.

However, this can be addressed by creating one’s own PCB. There are two ways

to utilize a PCB: it can be ordered by a company specializing in the production of

PCBs, or it can be created by an individual. Both have their own advantages and

disadvantages.

In order to etch a PCB, the PCB circuit layout of the portable unit would first be

plotted on a computer. The image would then be inverted. It would then be

printed on a laser printer, preferably on simple photo paper. At this point, the

copper-clad board would be cut to size, and the piece of paper placed on it, toner

side down. A hot iron would then be pressed onto the paper with heavy pressure.

After this, the paper-copper combination is placed into water. After a few hours,

the paper should be removed. After placing the combination in water again, all

remaining paper should be rubbed or otherwise removed. The combination is

then left to etch in a solution of ferrous chloride. Then, holes must be drilled, and

components soldered. At this point, the board should be complete.

While etching a PCB was an attractive option, given its elimination of the price

penalty commonly associated with PCBs, none of the group members had the

appropriate materials necessary to do as such. In addition, the lack of experience

meant that several boards would likely be wasted as a working board was

created. As such, the other option is more attractive – outsourcing production to

a company specializing in custom PCB production.

The company chosen was Sunstone Circuit’s PCB123. Although there is a cost

penalty, the final result is more professional looking, and will be as durable as

possible for any possible long term use of the portable unit. The PCB circuit

layout is detailed in Figure 3.6.3-1 below.